We review some old and present new results on isoperimetric-type problems on graphs and posets. Among these results are edge-isoperimetric problems for new graph families, new Macaulay posets, local-global principles, and some other relations between certain extremal graph and poset problems. The talk is based on the following papers: Ëdge isoperimetric problems on graphs", Ön an equivalence in discrete extremal problems", and Ä local-global principle for Macaulay posets", all available from http://math.uwsuper.edu/ sb/publications.html